ABSTRACT Anemia is a common medical condition in preterm infants. Previous studies show that neurodevelopmental outcomes of preterm infants are dependent in part on the degree of anemia. In a developmentally appropriately-timed neonatal mouse model, phlebotomy induced anemia (PIA) of the degree commonly seen in hospitalized preterm infants results in significant short-term dysfunction and long-term injury to multiple brain areas including the hippocampus, prefrontal cortex, striatum and cerebellum. Potential therapies for PIA include erythropoietin (rHuEPO) administration and red blood cell transfusion (RBCTX). Each therapy has the potential advantage to relieve tissue hypoxia induced by anemia, but also expose the rapidly developing premature neonatal brain to potential neuropathologic processes. Treatment with rHuEPO may be neuroprotective or alternatively, shunt limited neonatal iron reserves into RBCs and thus restrict iron delivery, leading to worsening brain iron deficiency (ID). Animal models of neonatal anemia due to ID demonstrate particularly profound effects on the developing brain, including its genome, metabolome, structure, intracellular signaling pathways, electrophysiology and behavioral output. RBCTX, while alleviating tissue hypoxia due to anemia, places the brain at risk for iron overload, inflammation and suppression of endogenous EPO production ? a potential neuronal growth factor. The overall research aim of this proposal is to evaluate whether rHuEPO treatment or RBCTX to relieve PIA in the newborn mouse pup between postnatal days (P) P3 and P14 improves regional brain development and function in the neonatal period and in young adulthood following resolution of anemia. This will be done by assessing the behavioral function, neurometabolome, and gene and protein expression in 4 brain regions in the neonatal and adult mouse that we have demonstrated in the previous 5 years are compromised by PIA. Aim 1 tests whether treatment of PIA with rHuEPO beginning either prior to the onset of anemia or once anemia is present rescues the developing brain from the adverse effects of untreated PIA. Aim 2 tests whether treatment of PIA with RBCTX initiated at the two hematocrit thresholds utilized in human trials results improves neurodevelopmental outcome in the mouse. A multi-tiered developmental neuroscience approach that spans gene expression to behavior is necessary provide the needed mechanistic understanding for the anticipated results of ongoing clinical studies by the Neonatal Research Network of the National Institutes of Child Health and Development and to model effects of PIA and its treatments on neurodevelopment.